The class was a pair of armored cruisers built for the German (Imperial Navy) in the 1900s. The two ships of the class, and , closely resembled the earlier s upon which they were based. The class incorporated slight incremental improvements, including a pair of extra boilers. The ships were easily distinguished from their predecessors by the addition of a fourth funnel. Though the additional boilers were meant to increase the ships' speed, both vessels failed to reach their designed top speed. In addition, the ships had comparatively light armament and thin armor protection, so they compared poorly with their foreign contemporaries, particularly the armored cruisers of their primary opponent, the British Royal Navy.

The two ships served in I Scouting Group, the reconnaissance force of the High Seas Fleet after they entered service in 1905–1906. During this period, and served stints as the group flagship and the deputy commander flagship, respectively. By the early 1910s, the first German battlecruisers had begun to enter service and was decommissioned in 1911 and placed in reserve; joined her in 1913. Both ships were reactivated after World War I broke out in July 1914. They were assigned to III Scouting Group, with as its flagship, and tasked with screening for the main body of the German fleet. In November, the German fleet made the raid on Yarmouth, but on return to port at Wilhelmshaven, the fleet encountered heavy fog and had to stop off Schillig. s commander decided that visibility had improved so he ordered his ship to get underway again, but she quickly struck two German mines and sank with heavy loss of life.

Roon-class cruiser

was transferred to the Baltic in April 1915 and participated in a series of offensive operations against Russian forces, including the attack on Libau in May, the Battle of the Åland Islands in July, and the Battle of the Gulf of Riga in August. The threat of British submarines led to her decommissioning in 1916, after which she was employed as a training ship and an accommodation vessel. Plans to convert her into a seaplane tender late in the war came to nothing owing to Germany's defeat in 1918, and she was stricken from the naval register in 1920 and broken up the following year.

Roon-class cruiser

Design

The Second Naval Law in Germany, passed in 1900, envisioned a force of fourteen armored cruisers for both service overseas in Germany's colonial empire and as scouts for the main battle fleet in German waters. The naval expansion program was primarily directed against the British Royal Navy, then the world's preeminent naval force. The previous armored cruiser design, the , provided the basis for the next pair of vessels to be built under the program. The design for the new ships, completed in 1901, were slight improvements over the s, with the primary changes being the addition of two boilers, which necessitated a longer hull and provided an increase by about . The design staff projected that the ships would gain in speed over the earlier cruisers, but in service, neither actually reached that speed. This failure was primarily the result of their length to breadth ratio, which was the result of limitations imposed by the dock facilities in Wilhelmshaven.

Roon-class cruiser

The -class ships shared many of the same layout characteristics as the contemporary German pre-dreadnought battleships, including a smaller main armament but heavier secondary battery than their foreign equivalents. And as with all of the preceding German armored cruisers, they received less armor protection than their opposite numbers in the British fleet. As a result, they compared unfavorably with their British contemporaries. The historian John Taylor describes the ships as "poorly protected and not a successful class in service." Further, they suffered the same fate as many pre-dreadnought type vessels completed in the mid-1900s, having been rendered obsolescent by the advent of all-big-gun warships like the British battlecruiser , launched in 1907. Despite their drawbacks, the s provided the basis for the follow-on , which proved to be far better fighting ships, more than a match for their British counterparts.

General characteristics and machinery

The ships of the class were long at the waterline and overall. They had a beam of and a draft of . and displaced normally, and at full load. Their hulls were constructed from transverse and longitudinal steel frames that formed a structure over which the steel hull plates were riveted. The hulls contained twelve watertight compartments and a double bottom that ran for sixty percent of the length of the ship.